Natural cheese traditionally is made by developing acidity in milk and setting the milk with a clotting agent, such as rennet, or by developing acidity to the isoelectric point of the protein. The set milk is cut and whey is separated from the block. The curd may be pressed to provide a cheese block. Curing typically takes place over a lengthy period of time under controlled conditions. Cheddar cheese, for example, is often cured for a number of months, and may be cured for a period in excess of one year, to obtain the full flavor desired.
Numerous reports have been published implicating several compounds to be important in the development of cheese flavor in cheese products. The main classes of compounds thought to contribute to flavor generation in cheese include amino acids, peptides, carbonyl compounds, fatty acids, and sulfur compounds. Urbach, “Contribution of Lactic Acid Bacteria to Flavor Compound Formation in Dairy Products,” Int'l Dairy J., 1995, 5:877-903. Several volatile compounds including fatty acids, esters, aldehydes, alcohols, ketones, and sulfur compounds were indicated as contributing to the aroma of various cheeses. Production of several of these aroma and flavor compounds has been attributed to multiple enzymatic reactions and chemical reactions that take place in a sequential manner in ripening cheese.
Various microorganisms have been identified and selected for their ability to produce particular flavors in a cheese-ripening environment. These flavors arise through a series of enzymatic steps. For example, in cheese, degradation of proteins by proteases and peptidases can lead to the production of peptides and free amino acids. These precursors are shuttled through subsequent enzymatic reactions resulting in the formation of flavor compounds. An understanding of these reactions helps in the creation of flavors of a desired cheese type. Fox, P., Cheese: Chemistry, Physics and Microbiology, Kluwer Academic/Plenum (publishers), pp. 389-483, 1993.
Cheese manufacturers are interested in developing cheese products requiring less storage time before they are ripe enough for commercial distribution. Cheese makers have used a wide variety of different techniques in efforts to accelerate the cheese curing or ripening process. U.S. Patent Publication 2001/0024667 provides a summary of a number of these techniques used for accelerating ripening of hard block cheeses.
U.S. Pat. No. 4,244,971 describes a process and product for the rapid manufacture of cheese products, in which a cultured component is prepared and mixed with a milk protein concentrate and a fat concentrate; this mixture is fermented to provide a cheese material capable of being made into process cheese-type products by conventional cheese cooking techniques. The cultured component is prepared by proteolyzing milk protein and lipolyzing milk fat, and forming a mixed fermentate of these hydrolyzed materials. The mixed fermentate is combined with a cheese starter culture and fermented to give the cultured component.
U.S. Pat. No. 5,462,755 describes methods and compositions for flavor enhancement and development in a cultured dairy product using identification and selection of fat fractions from sources such as milk fat (butter) for use as flavor precursors. Another approach used to avoid lengthy cheese ripening periods has been to make a cultured cheese concentrate (“CCC”) having more intense cheese flavor, and then use it as a cheese-flavoring agent in another bulk material. CCCs have been manufactured that attain full cheese flavor development within a number of days instead of months. These CCCs are added to other bulk foods, such as process cheeses or snack foods, to impart or intensify a cheese flavor in them.
U.S. Pat. No. 4,708,876, for example, describes methods for the manufacture of such cheese-flavorings and enzyme-modified cheeses (EMCs). Typically the process involves a dairy substrate that is cultured with a lactic culture followed by addition of various proteases, peptidases, and lipases. Cheese flavored concentrates can be obtained from milk as a starting material, instead of cheese curds, or without formation of whey by-product. U.S. Pat. No. 4,500,549 describes use of whey-derived substrates to generate cheese flavorings characteristic of aged cheese. However, the prior above-mentioned processes produce an enhancement of cheese flavor but do not produce targeted cheese flavored components. U.S. Pat. No. 6,406,724 describes methods for producing a natural biogenerated cheese flavoring system that can be used to prepare different cheese products/derivatives. The cheese flavoring system is made up of different components which are combined in different ratios to provide specific favor profiles.
U.S. Pat. No. 4,670,267 describes the production of a fermented whey butter flavoring prepared by fermentation of a sweet whey based medium comprising water, sweet-whey solids, a fortifier selected from citric acid, pyruvic acid, and salts thereof, and a fatty compound enriching agent described preferably as milkfat or lipolyzed butterfat. The sweet whey based medium is pasteurized, inoculated with a starter culture, and incubated to yield an aqueous composition described as a butter flavoring. This patent describes adding milkfat, such as heavy cream, to the sweet whey medium to a concentration (preferably at a level of about 2 percent or less); according to the patent, no further flavor improvement is attainable at higher milkfat concentrations. Alternatively, this patent describes adding lipolyzed butterfat to the sweet whey medium preferably at about 0.2 percent.
European Patent Publication EP 0 981 965 A1 describes a highly flavored component for use in cheese manufacture and a method for producing it in a relatively short period of time. An aqueous, acidified protein and fat cheese flavor precursor is provided by mixing a dried or concentrated protein source, a fat source, an acid source, and water. An enzyme system including a lipase, a protease, and a peptidase is then added to the substrate. The fat source is described as preferably being a milkfat such as anhydrous milkfat, butter, or cream. The protein source is described as preferably being a dairy ingredient such as milk protein concentrate, whey protein concentrate, dried whey, and non-fat dry milk. Before treatment with the enzyme system, the cheese flavor precursor has 5 to 30 percent protein, 10 to 40 percent fat, and 0 to 10 percent lactose. The precursor is treated for a time sufficient to provide a highly developed cheese flavor in the precursor. The precursor is then heated for a time sufficient to inactivate the enzyme system and provide a highly flavored component.
However, these prior processes do not produce enhancements that target specific cheese flavor components.
More recently, a natural biogenerated cheese flavoring system has been developed that can be used to prepare different cheese products/derivatives. This modular approach to flavor creation is described in U.S. Pat. No. 6,406,724. The cheese flavoring system includes different flavor components which are combined in different ratios to provide specific flavor profiles in the cultured cheese concentrate products. U.S. Pat. No. 6,562,383 describes a process for producing a flavored cheese that does not require curing or aging using the flavor components of U.S. Pat. No. 6,406,724.
The effects of bacteriocin producers as adjunct cultures to thermophilic starters of high aminopeptidase activity, more sensitive to lysis by bacteriocins than mesophilic starters, on ripening speed in semihard and hard cheeses has been described in the literature. The use of a bacteriocin-producing E. faecalis culture in a cheese starter system for making a semi-hard cheese at low pH values (below 5.5) for enhancement of cheese flavor after a relatively long ripening period (viz., 21 to 35 days), has been described by Oumer et al., “Defined starter system including a bacteriocin producer for the enhancement of cheese flavor,” Biotechn. Techniques, 13: 267-270, 1999. The use of live cultures having high levels of proteolytic enzymes and peptidolytic enzymes to debitter enzyme modified cheeses (EMCs) also has been described (see, e.g., U.S. Pat. No. 6,214,585).
Despite these developments, a need still exists for cheese flavoring components that can be derived from readily available, cost-attractive natural substrate materials, such as whey sources, and from which flavor may be developed that is highly heat-stable. The present invention provides heat-stable flavor components useful for cultured cheese concentrates and methods for their manufacture that meets these and other desirable needs as well as provides other benefits.